Optical recording medium with audio data from coder using bitrate real-time lossless encoding by moving excess data amounts

ABSTRACT

A recording medium encoded with audio data encoded using a lossless encoding apparatus. The lossless encoding apparatus includes a lossless compression unit which losslessly compression encodes the audio data stored in an input buffer in units of predetermined data and outputs the encoded data in sequence, and an output buffer which stores the encoded audio data output from the lossless compression unit. A bitrate controller divides a plurality of the encoded audio data stored in the output buffer into first data having a data amount exceeding the maximum bitrate and second data having a data amount less than the maximum bitrate, divides the first data into third data being the encoded audio data having a data amount of the maximum bitrate and fourth data being the encoded data of the portion exceeding the maximum bitrate, and controls the output buffer so that the fourth data is output together with the second data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of application Ser. No.09/907,966, filed Jul. 19, 2001, which issued as U.S. Pat. No. 6,546,370which is a divisional of application Ser. No. 09/304,264, filed May 6,1999, which issued as U.S. Pat. No. 6,385,587, which claims the benefitof Korean Application No. 98-16182, filed May 6, 1998, in the KoreanPatent Office, the disclosures of which are incorporated herein byreference. This application is related to U.S. patent application Ser.No. 09/588,755, which issued as U.S. Pat. No. 6,477,501, U.S. patentapplication Ser. No. 09/907,964, which issued as U.S. Pat. No.6,480,829, and U.S. patent application Ser. No. 09/907,965, which issuedas U.S. Pat. No. 6,473,736.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lossless encoding and decodingsystem, and method therefor, and more particularly, to a losslessencoding and decoding system including a lossless encoding apparatus anda lossless decoding apparatus in which encoded data can be decoded on areal-time basis.

2. Description of the Related Art

In general, a digital audio signal is obtained from an analog audiosignal by means of a pulse code modulation method, in order to representaudio information with the number of channels, the number of bits and asampling frequency according to DVD-audio standards. However, since adigital audio signal includes redundancy data, it is required to uselossless compression encoding methods, in order to shorten a recordingtime of a digital audio signal with respect to a digital versatile disc(DVD) and improve a bitrate.

A representative example of lossless compression encoding methods is theHuffman coding method, in which input data having a higher frequency ofoccurrence is assigned with a relatively shorter length of codeword andinput data having a lower frequency of occurrence is assigned with arelatively longer length of codeword. In the case that a digital audiosignal is losslessly compressed by the Huffman coding method, it is moreefficiently coded than in the case that only a linear pulse codemodulation (PCM) method is used.

Meanwhile, a predictor is used in the case that input data haspredictable properties. The predictor determines prediction datacorresponding to new input data using previous input data, and then usesa method for compressing a difference between the prediction data andthe new input data. In the case that such a predictor is additionallyused in the above-described lossless compression unit, an encodingefficiency with respect to the digital audio signal can be furtherenhanced.

When the above-described conventional lossless encoding method is used,a bitrate of the encoded data varies according to the degree of theproperty and randomness of input data, although a bitrate of the inputdata is constant. Thus, since conventional lossless coding methodsrequire a very large capacity of buffers, in the case of datacompression and decompression, it is difficult to encode or decode datain real-time. In addition, although a buffer capacity is increased inorder to solve the above problem, a delay in decoding still remains.

SUMMARY OF THE INVENTION

To solve the above problems, it is an object of the present invention toprovide a lossless encoding apparatus for encoding data on a real-timebasis.

It is another object of the present invention to provide a losslessdecoding apparatus for decoding encoded data on a real-time basis.

It is still another object of the present invention to provide alossless encoding and decoding system having a lossless encodingapparatus and a lossless decoding apparatus in which encoded data can bedecoded on a real-time basis.

Additional objects and advantages of the invention will be set forth inpart in the description which follows and, in part, will be obvious fromthe description, or may be learned by practice of the invention.

To accomplish the above and other objects of the present invention,there is provided a lossless encoding apparatus for encoding input audiodata, comprising an input buffer to store the input audio data; alossless compression unit to losslessly compression encode the audiodata stored in the input buffer in units of predetermined data andoutput the encoded audio data in sequence; an output buffer to store theencoded audio data output from the lossless compression unit; and abitrate controller to distinguish each predetermined data unit of theencoded audio data stored in the output buffer as first data having adata amount exceeding a maximum bitrate or second data having a dataamount less than the maximum bitrate, dividing the first data into thirddata being the encoded audio data having a data amount of the maximumbitrate and fourth data being the encoded data of a portion of the firstdata exceeding the maximum bitrate, and control the output buffer sothat the fourth data is output together with the second data from theoutput buffer.

To further accomplish the above and other objects of the presentinvention, there is provided a lossless decoding apparatus to decodeinput data to restore audio data, comprising an input buffer to storethe input audio data and maintain an input sequence thereof; a losslessrestorer to losslessly restore the input audio data output from theinput buffer, to generate the restored audio data; a buffer controllerto control the input buffer, so that first data having no identificationinformation among the input audio data stored in the input buffer issupplied to the lossless restorer and second data having identificationinformation is combined with third data having the same identificationinformation and supplied to the lossless restorer, wherein the firstdata has a data amount by which a result obtained by lossless encodingof the input audio data of a predetermined data unit does not exceed amaximum bitrate, and the second data and third data form fourth data bywhich a result obtained by lossless encoding of the input audio data ofa same predetermined data unit exceeds the maximum bitrate, and whereinthe second data is encoded audio data having a data amount of themaximum bitrate among the fourth data and the third data is encodedaudio data of the portion exceeding the maximum bitrate among the fourthdata; and an output buffer to store and output the restored audio datagenerated in the lossless restorer.

To still further accomplish the above and other objects of the presentinvention, there is provided a lossless encoding and decoding system forencoding and decoding input audio data, comprising a lossless encodingapparatus comprising a first input buffer to store the input audio data,a lossless compression unit to losslessly compression encode the audiodata stored in the first input buffer in units of predetermined data andoutput the encoded audio data in sequence, a first output buffer tostore the encoded audio data output from the lossless compression unit,and a bitrate controller to distinguish each predetermined data unit ofthe encoded audio data stored in the output buffer as first data havinga data amount exceeding a maximum bitrate or second data having a dataamount less than the maximum bitrate, dividing the first data into thirddata being the encoded audio data having a data amount of the maximumbitrate and fourth data being the encoded data of a portion of the firstdata exceeding the maximum bitrate, add identification information tothe third data and fourth data to indicate which of the third data andfourth data are from the same predetermined data units, and control thefirst output buffer so that the fourth data is output together with thesecond data from the first buffer, and the second through fourth dataare output as a bitstream, and a lossless decoding apparatus comprisinga second input buffer to store the bitstream in a same input sequencethereof, a lossless restorer to losslessly restore the bitstream outputfrom the second input buffer, generate the input audio data, a buffercontroller to control the second input buffer so that the second datahaving no identification information among the data stored in the secondinput buffer is supplied to the lossless restorer and the third data andfourth data having the same identification information are combined andsupplied to the lossless restorer, a second output buffer to store andoutput the restored input audio data generated in the lossless restorer.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and other advantages of the present invention willbecome more apparent by describing in detail the structures andoperations of the present invention with reference to the accompanyingdrawings, in which:

FIG. 1 is a block diagram showing a lossless encoding apparatusaccording to an embodiment of the present invention;

FIG. 2 is a conceptional view for explaining the operation of a bitratecontroller shown in FIG. 1;

FIG. 3 shows a structure of a bitstream output from an output buffershown in FIG. 1; and

FIG. 4 is a block diagram showing a lossless decoding apparatuscorresponding to the lossless encoding apparatus shown in FIG. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

A preferred embodiment of the present invention will be described withreference to the accompanying drawings, in which elements having thesame reference numerals perform the same functions.

In FIG. 1 showing a lossless encoding apparatus according to anembodiment of the present invention, an input buffer 11 stores digitalaudio data input from an external source and supplies the stored audiodata to a lossless compression unit 13 in the same sequence as its inputsequence. The lossless compression unit 13 losslessly compresses andencodes the audio data supplied from the input buffer 11 in each ofpredetermined data units. In this embodiment of the present invention,for example, a frame is used as a predetermined data unit. Also, thelossless compression unit 13 losslessly compresses and encodes the audiodata by means of a lossless compression encoding method such as awell-known Huffman encoding method. The audio data encoded by thelossless compression unit 13 is input to an output buffer 15. The outputbuffer 15 stores the input encoded audio data. The output buffer 15stores the encoded audio data in such a pattern that the encoded audiodata corresponding to a random frame can be distinguished from theencoded audio data corresponding to the other frames. A bitratecontroller 17 stores a maximum bitrate determined based on a bitrateresulting from losslessly encoding all of the audio data correspondingto an audio track of a recording storage medium such as a DVD. Thebitrate controller 17 controls the output buffer 15 in such a mannerthat the encoded audio data stored in the output buffer 15 is output atan output bitrate which is equal to or less than the maximum bitrate.

Referring to FIG. 2, the operation of the bitrate controller 17 will bedescribed below. The bitrate controller 17 distinguishes each frame ofthe encoded audio data stored in the output buffer 15 into first datahaving a data amount exceeding the maximum bitrate or second data havinga data amount not exceeding the maximum bitrate. By the above division,for example, the encoded audio data of the frames of frame numbers 6, 7and 10 shown in FIG. 2 is defined as first data. The bitrate controller17 divides respective first data into third data being the encoded audiodata having a data amount of the maximum bitrate and fourth data beingthe encoded audio data of the portion exceeding the maximum bitrate. Thefourth data is shown as hatched portions in FIG. 2. The bitratecontroller 17 adds identification information by which the fourth dataand the third data corresponding to the fourth data can be distinguishedfrom data of the other frames, to the fourth data and the third datacorresponding to the fourth data. Then, the bitrate controller 17controls the output buffer 15 in such a manner that the fourth data isoutput together with the second data of the other frame from the outputbuffer 15. The bitrate controller 17 determines the second data to whichthe fourth data is added, so that the combined data does not exceed themaximum bitrate.

In this embodiment of the present invention, the bitrate controller 17selects a particular frame temporally preceding the frame of the fourthdata, and controls the output buffer 15 in such a manner that the fourthdata is output together with the second data of the selected (other)frame. In this case, the bitrate controller 17 selects a preceding framein which to add the fourth data based on the bitrate corresponding to anumber of frames preceding the frame of the fourth data. In response tothe control of the bitrate controller 17, the output buffer 15 outputsthe second data, both the second and fourth data, or the third data inthe form of a bitstream, in correspondence to a respective frame of theencoded audio data supplied from the lossless compression unit 13. Thus,in the case of the frames having the numbers shown in FIG. 2, the outputbuffer 15 outputs a bitstream as shown in FIG. 3, wherein the bitstreammay be recorded on a recording medium such as a DVD. In FIG. 3, theframes which are not hatched are frames output from the output buffer 15in the same sequence as that input to the output buffer 15 from thelossless compression unit 13, and the hatched portions show the fourthdata added to the second data of a frame temporally preceding theoriginal frame.

FIG. 4 is a block diagram showing a lossless decoding apparatus forrestoring the bitstream output from the lossless encoding apparatusshown in FIG. 1 and perhaps stored on a recording medium such as a DVD.In FIG. 4, an input buffer 41 stores bitstream data generated in theencoding apparatus of FIG. 1 in the same sequence as its input sequence.A buffer controller 43 controls the input buffer 41 in order to outputthe data stored in the input buffer 41 to a lossless restorer 45. Underthe control of the buffer controller 43, the second data is output tothe lossless restorer 45 without change, and the fourth data is combinedwith the third data corresponding to the fourth data, based onidentification information added to the third data and the fourth data.The combined first data is output to the lossless restorer 45. Here, thebuffer controller 43 determines the sequence of the first data and thesecond data both output to the lossless restorer 45 based on the seconddata and the third data. Thus, in the case that the second data precedesthe third data among the data of the bitstream input to the input buffer41, the second data is output to the lossless restorer 45 and then thefirst data corresponding to the third data is output to the losslessrestorer 45. As a result, the input buffer 41 can supply the stored datato the lossless restorer 45 so that the lossless restorer 45 can restoredata without any delay.

The lossless restorer 45 performs a reverse process of a signalprocessing in the above-described lossless compression unit 13 in orderto restore the digital audio data, and outputs the restored audio datato an output buffer 47. The output buffer 47 stores the digital audiodata supplied from the lossless restorer 45 and supplies the storeddigital audio data to a following device (not shown).

Since it is apparent to those who are skilled in the art that the abovelossless encoding apparatus and the above lossless decoding apparatuscan be employed in a lossless encoding and decoding system, although ithas not been shown in the drawings and described in the specification, adetailed description of such a lossless encoding and decoding system isomitted here.

As described above, the lossless encoding and decoding system includingthe lossless encoding apparatus and the lossless decoding apparatuscontrols the bitrate of the encoded audio data so that the encoded audiodata can be decoded on a real-time basis. Thus, the present inventioncan be used in a real-time system with limited bitrate as in a discplayback device or a communications channel.

Although a preferred embodiment of the present invention has been shownand described, it would be appreciated by those skilled in the art thatchanges may be made in this embodiment without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

What is claimed is:
 1. A recording medium comprising: a first one ofdata units encoded in real time at or below a predetermined data amountcomprising a first original data unit and a first part; and a second oneof the data units at or below the predetermined data amount encodedlosslessly in real time in a sequence after said first data unit, saidsecond data unit and the first part comprising a second original dataunit prior to encoding that exceeded the predetermined data amount,wherein said first data unit and/or said second data unit refer to eachother as to be decoded in real time in the sequence and restored to thefirst and second original data units in the sequence.
 2. The recordingmedium according to claim 1, wherein the first part and said second dataunit have identification information added thereto such that, duringdecoding, the first part and said second data unit are combined andrestored as the second original data unit.
 3. The recording mediumaccording to claim 2, further comprising additional data units disposedbetween said first and second data units in the sequence.
 4. Therecording medium according to claim 3, wherein said additional dataunits comprise a third data unit and a fourth data unit, the third dataunit comprising a third original data unit and a second part, where thefourth data unit is encoded sequentially after the third data unit, andthe fourth data unit and the second part comprise a fourth original dataunit prior to encoding.
 5. The recording medium according to claim 2,wherein the encoded data comprises encoded audio data.
 6. The recordingmedium of claim 2, wherein said first data unit, the first original dataunit, and said second data unit have sizes at or below a predeterminedlimit, and the second original data unit has a size greater than thepredetermined limit with the first part being an amount in excess of thepredetermined limit.
 7. The recording medium according to claim 1,wherein the first part and said second data unit refer to each othersuch that, during decoding, the first part and said second data unit arecombined and restored as the second original data unit.
 8. The recordingmedium according to claim 7, wherein said first data unit, the firstoriginal data unit, and said second data unit have sizes at or below apredetermined limit, and the second original data unit has a sizegreater than the predetermined limit with the first part being an amountin excess of the predetermined limit.
 9. The recording medium accordingto claim 1, further comprising additional data units disposed betweensaid first and second data units in the sequence.
 10. The recordingmedium according to claim 9, wherein said additional data units comprisea third data unit and a fourth data unit, the third data unit comprisinga third original data unit and a second part, where the fourth data unitis encoded sequentially after the third data unit, and the fourth dataunit and the second part comprise a fourth original data unit prior toencoding.
 11. The recording medium according to claim 10, wherein saidfirst data unit, the first original data unit, said second data unit,the third data unit, the third original data unit, and the fourth dataunit have sizes at or below a predetermined limit, and the secondoriginal data unit and the fourth original data unit have sizes greaterthan the predetermined limit, with the first part and the second partbeing amounts in excess of the predetermined limit.
 12. The recordingmedium according to claim 9, wherein the first part and said second dataunit refer to each other such that, during decoding, the first part andsaid second data unit are combined and restored as the second originaldata unit.
 13. The recording medium according to claim 9, wherein saidfirst data unit, the first original data unit, and said second data unithave sizes at or below a predetermined limit, and the second originaldata unit has a size greater than the predetermined limit with the firstpart being an amount in excess of the predetermined limit.
 14. Therecording medium according to claim 1, wherein the encoded datacomprises encoded audio data.
 15. The recording medium of claim 1,wherein said first data unit, the first original data unit, and saidsecond data unit have sizes at or below a predetermined limit, and thesecond original data unit has a size greater than the predeterminedlimit with the first part being an amount in excess of the predeterminedlimit.
 16. A recording medium comprising: a first one of losslesslyencoded data units comprising a first original data unit and a firstpart; and a second one of the data units encoded sequentially after saidfirst data unit, said second data unit and the first part comprising asecond original data unit prior to encoding, wherein said first andsecond data units are losslessly encoded in real time by losslesslycompression encoding input audio data including the first original dataunit and the second original data unit in the sequence, determiningwhether the first and second original data units have data amounts inexcess of a maximum bitrate; and combining the first part which isexcess data amounts from the second original data unit with the firstoriginal data unit which has data amounts less than the maximum bitrateto produce said first data unit and said second data unit.
 17. Therecording medium according to claim 16, wherein the combining the excessdata amounts comprises moving the first part to the first original dataunit which precedes the second original data unit in the sequence. 18.The recording medium according to claim 16, wherein the encoding furthercomprises outputting said first and second data units in the sequenceafter said combining the excess data amounts.
 19. The recording mediumaccording to claim 16, wherein the encoding is such that, duringdecoding, the first part is moved back to said second data unit toreform the second original data unit, and the encoded input audio datais losslessly restored after the first part is moved back to said seconddata unit.
 20. The recording medium of claim 19, wherein the encodingfurther comprises including identification information in the first partand said second data unit such that, during decoding, the first part ismoved back to said second data unit to reform the second original dataunit having data amounts in excess of the maximum bit rate in accordancewith the identification information.